I run a global telecommunications company.

At a recent Mobile World Congress, I met people who were conducting research at different European institutions. They told me that the behaviour of atoms and photons could revolutionise the field of communications, for example by improving data security.

When I got back home, I asked our company's engineers to study how quantum physics could benefit our business.

I really like to go hiking, and satellite navigation systems, such as GPS and Galileo, help me not get lost.

It is amazing to be able to see my position on the map to an accuracy of just a few metres. That would be impossible if navigation systems' satellites did not have atomic clocks. The quantum nature of atoms ensures these clocks' extreme precision, which translates into a minimal margin of error on our location.

Since I live in a small mountain village with few shops, I have got used to buying everything I need online. But there are many people in the village, including my grandmother, who prefer to drive an hour to the city rather than enter their details on the internet, because they are afraid of hacker attacks.

Although this is a major danger, I am not worried. I have read that there are many people dedicated to studying new ways to improve the communications security. It seems the most promising techniques are related to the exotic properties of quantum physics!

In some experiments, the result does not allow us to distinguish which path the particle has taken: it is as if it were traveling along two paths at once! What we can observe is the effect of the interference between the two paths.

If we block one path, we no longer see interference, even though the particle has gone through the open path. It is as if it knew what is happening on the other path without going along it.

Applications: detecting and/or observing objects without interacting.

Quantum physics describes the world at both atomic and molecular scales: in recent years, the scientific community has learned to take advantage of phenomena that appear at microscopic scale to create new technologies.

Quantum technologies are expected to improve the way in which some physical systems are studied, communications security, computing speed and sensor sensitivity.

With more than half of its groups working in these fields, ICFO is pooling its efforts with groups from other research centres and companies, playing an active role in networks at local (Complementary Plan - Quantum Communications) and international level (European Quantum Flagship), which aim to accelerate the arrival of these technologies in society.

In order to send an encrypted message, you must have a key to encrypt and decrypt the message. The challenge for the receiver and the sender is to share the key without it being intercepted.

Thanks to superposition and the effect of measurement on quantum systems, we can share keys securely and remotely.

Quantum key distribution systems can even detect the eventual presence of spies.

There are various companies (among which LuxQuanta and Quside,  ICFO spin-off companies) that already offer cryptographic commercial services based on quantum physics.

Many of the principles of quantum physics defy common sense (e.g. particles must have a well-defined property) or other physical theories (instant action at a distance is not possible). This made physicists wonder if quantum theory was incomplete.

John Bell ended this philosophical debate by designing an experiment that would make it possible to exclude possible alternative explanations to quantum physics that did not defy intuition.

Starting in the 1980s, many Bell tests were conducted that confirmed the validity of quantum physics.

We are used to the fact that measuring does not change the properties of objects at all, but at the quantum level, measuring can change the properties of what is being measured. In fact, if the particle is in a superposition of two states, the measurement causes the collapse of the superposition and as a result we observe only one well-defined one state.

If we cannot avoid the effect of our presence as observers on the system, how can we really know anything for sure?

Fundamental research, such as that in certain fields of quantum physics, requires economic resources that do not translate into short-term applications. On the other hand, if we limit research to sectors that can give a rapid economic return, it is difficult to reach the solid general scientific basis that underpins technological progress.

How can we solve this "vicious circle"?

Their applications in all fields of human activity will radically change our lives, just as electricity and electronics once did. We must invest as much as we can in their development, to make them commercially viable as soon as possible. 

We should not be fooled by illusory promises. We have gone very far with traditional technologies and we still have a long way to go: we should keep the current investment in quantum technologies at the same level. Let scientists do their work and continue to research, focusing on maintaining and improving the technologies that we already have. 

Research into quantum physics and its applications is positive, but we currently have other far more important and pressing issues, such as hunger, poverty, wars and terrorism. Let us maintain research, but invest our money to find solutions to the major problems our society has today.  

Quantum technologies are very promising, but if they are to be effective, they require solid knowledge of their foundations. We should invest in fundamental research: a better understanding of the foundations of quantum physics will naturally lead to the development of its applications.